A solid block detergent composition is described which can be dispensed with a water spray to form an aqueous detergent for cutting and removing grease, removing and suspending soils and rinsing easily leaving cleaned ware. The aqueous detergent concentrate can be used in a cleaning liquid having exceptional soil, particularly grease removing properties with stable foam properties. The solid block detergent contains a package of surfactants including a neutralized anionic surfactant with either one or a mixture of an alkali and alkaline earth metal salt thereof and an alkylpolyglycoside. The active ingredients and polyethylene glycol as a hardening agent are dispersed in a matrix which hardens to form a solid block.

The application relates to solid detergent materials. Largely, the invention relates to a solid detergent composition containing a detergent formulation dispersed in an organic solidification matrix. The combination of ingredients provides excellent soil removal, improved grease cutting and controlled foaming in an aqueous detergent composition made from the solid.
The development of solid block cleaning compositions has revolutionized the manner in which detergent compositions are dispensed by commercial and institutional entities that routinely use large quantities of cleaning materials. Solid block compositions offer unique advantages over the conventional liquids, granules or pellet forms of detergents, including improved handling, enhanced safety, elimination of component segregation during transportation and storage, and increased concentrations of active components within the composition. Because of these benefits, solid block cleaning compositions, such as those disclosed in Fernholz, et al., U.S. Pat. Nos. Re 32,763, 32,818, 4,680,134 and 4,595,520, have quickly replaced the conventional composition forms in commercial and institutional markets. Another sodium hydroxide and sodium carbonate cast solid process using substantially hydrated sodium materials was disclosed in Heile et al. U.S. Pat. Nos. 4,595,520 and 4,680,134. Further, pelletized materials are shown in Gladfelter et al., U.S. Pat. Nos. 5,078,301, 5,198,198 and 5,234,615. Extruded materials are disclosed in Gladfelter et al., U.S. Pat. No. 5,316,688. The solid block format is a safe, convenient and efficient product format.
Various hardening mechanisms have been used in cleaning and sanitizing compositions for converting a fluid composition to a solid mass for containment and modification of the solubility of the active ingredients during use. For example, the active ingredients may be combined with the hardening agent under melting temperatures, commonly referred to as a xe2x80x9cmolten process,xe2x80x9d to achieve a homogeneous mixture, wherein the melt is then poured into a mold and cooled to a solid form.
U.S. Pat. No. 5,019,346 to Richter, for example, discloses a solid block drain treatment product formed by heating a mixture containing a chemical sanitizer and a hardening agent such as urea or an alkyl amide such as stearic monoethanolamide or stearic diethanolamide, and decanting the melt into containers. Morganson, U.S. Pat. No. 4,861,518, discloses a solid cleaning concentrate formed by heating an anionic or nonionic surfactant system with a hardening agent such as polyethylene glycol, at about 130-150xc2x0 F. (54 to 66xc2x0 C.) to form a melt. The melt is combined with other ingredients including a solubilizer and an alkali, to form a homogeneous mixture, and the molten mixture then poured into a capsule container to cure or harden. U.S. Pat. Nos. 4,595,520 and 4,680,134 to Heile et al. disclose a solid alkaline detergent formed from an aqueous emulsion containing a sodium condensed phosphate hardness sequestering agent and an alkaline builder salt such as sodium hydroxide, which is solidified by incorporating a hydratable hardening agent such as an anhydrous sodium carbonate and/or sodium sulfate. Preferably, the emulsion is heated to form a molten mass, and then cooled to effect solidification. U.S. Pat. No. 5,064,554 to Jacobs et al. discloses a solid detergent in the form of a fused block manufactured by preparing a melt of alkaline metal silicate, alkali metal hydroxide, optionally water, an active chlorine donor and/or an organic complexing agent, combining the melt with a penta-alkali metal triphosphate, introducing the melt into a flow mixer, and pouring the molten mixture into a mold to solidify.
Solid block cleaning and sanitizing compositions and rinse aids provide a significant improvement over the conventional liquid, granular and pelletized cleaning compositions. Although the molten process is useful for preparing solid block compositions, time and expense would be saved if heating and cooling of the composition could be minimized or eliminated from the process, and higher viscosities could be used. Also, lower process temperatures would better facilitate the use of heat-sensitive ingredients in cleaning compositions. In addition, less sturdy packaging would be required if the processed mixture could be packaged at a lower temperature. Furthermore, eliminating molten temperatures would avoid swelling and deformation of the solid product.
Various attempts have been made to manufacture cleaning compositions by an extrusion process. U.S. Pat. No. 5,061,392 to Bruegge et al., for example, discloses a method of forming a detergent composition having a paste-like consistency, by combining a first aqueous solution containing a potassium tripolyphosphate and a second aqueous solution containing a water-soluble, sodium-based detergent builder, namely sodium hydroxide. Upon mixing, the viscosity of the mixture rapidly increases to form a highly viscous paste. In another extrusion method, as disclosed in U.S. Pat. No. 4,933,100 to Ramachandran, an organic detergent of particulate or patty form is formed by kneading together a synthetic organic detergent, a hydratable builder salt such as sodium tripolyphosphate, and water. The mixture is passed through an extruder and forced through openings at or slightly above room temperature and a low pressure to form a rod-shaped extrudate. A disadvantage of these processes is that a caustic, hydratable alkaline source is required to facilitate hardening of the processed composition after extrusion.
Richter. U.S. Pat. Nos. 5,436,008, 5,243,719 and others generally teach the use of polyethylene glycol materials as a component of a hardened composition.
The prior art shows a variety of liquid detergent compositions. Exemplary disclosures include Kennedy et al., U.S. Pat. No. 3,954,660 which disclose a slurry comprising a surfactant package and other components in a flowable mixture. Hellyer et al., U.S. Pat. No. 4,133,779 teach a liquid detergent composition comprising a semipolar nonionic detergent and an alkali metal salt of an anionic detergent useful in cleaning methods. Thomas et al., U.S. Pat. No. 5,571,459 teach a liquid emulsion that has a surfactant package that can include a magnesium salt of an anionic sulfate such as lauryl sulfate. Sajic et al., U.S. Pat. Nos. 5,616,781 and 5,637,758 teach liquid detergent compositions comprising a critical amount of a divalent cation and a minimum amount of an alpha-sulfonated methyl ester of a fatty acid, anionic surfactants and foam stabilizers in a pourable flowable mixture. Burdon et al., U.S. Pat. No. 5,635,466 disclose a concentrated aqueous surfactant solution comprising a magnesium salt of an alkyl ether sulfate. The material can take the form of a magnesium salt or a mixed magnesium ammonium salt. Similar liquid or granular detergent compositions are shown in Rolfes et al., WO 92/06156; Faber, EP 673 993; Herbots et al., GB 2 144 763; and Fu et al. WO 92/06157. Dawson et al., U.S. Pat. No. 4,235,758; Bernardino et al. U.S. Pat. No. 4,681,704; Simion et al., U.S. Pat. Nos. 4,923,635 and 5,096,622: disclose pourable stable clear liquid detergent compositions containing ingredients including both magnesium salts of anionic materials and sodium salts of anionic materials.
Gerritsen et al., U.S. Pat. No. 4,435,317 teach a stable liquid detergent composition containing a surfactant package comprising a magnesium or magnesium ammonium salt of anionic materials.
Misselyn et al., U.S. Pat. No. 5,604,195 disclose a liquid pourable cleaning composition that has a surfactant package and a small amount of either a polyvinyl pyrrolidone or a polyethylene glycol which polymeric materials are used at an amount of less than about 10% as grease release agents. The Misselyn et al. liquid materials can also contain magnesium salts.
Fujita et al. U.S. Pat. No. 5,062,986 and Kacher et al., U.S. Pat. No. 5,262,079 disclose soap bars. Fujita et al. use a water soluble polyester polymer material to solidify typical soap formulations. Kacher et al. utilize a mixed metal salt of a free monocarboxylic acid comprising 35 to 80 wt % of the mixture to form a solidified soap bar.
Cripe et al., U.S. Pat. No. 5,376,310; Ofsu-Asanta et al., U.S. Pat. No. 5,474,710; and Mao et al., U.S. Pat. No. 5,599,400 teach light duty liquid or gel materials comprising a surfactant package and magnesium salts of anionic materials.
Aqueous cleaning compositions have commonly been used in applications including hospital, household, institutional and industrial services, hand and body soaps. laundry soaps, warewashing and housekeeping surfaces. Typically, these cleaning materials are made by diluting liquid or gelled materials to form a use solution. Many such solutions have had some success in the past, however, a substantial need in this art exists to manufacture an easily used concentrate having minimal water and a high actives concentration, excellent soil, e.g. grease, removal properties and controlled foaming. Many prior art materials even in a concentrate form contain substantial amounts of water which is difficult to manufacture, transport and sell. The materials also may have some soil removal properties but improving grease removal and hard surface cleaners is a continuing need or requirement. Further, the manufacture of materials that produce useful foam in the presence of large quantities of greasy soil is a continuing challenge for this marketplace.
We have found that many of the needs can be met by forming a solid block detergent composition with high active content, minimal water content having the active ingredients dispersed in a hardening agent, e.g. polyethylene glycol (PEG), to form a solidification matrix. We have found that the useful active materials can include an anionic surfactant wherein the surfactant is neutralized with an alkali metal, an alkaline earth metal species, or, preferably, a mixture thereof. The neutralized anionic can be beneficially combined with a surfactant or surfactant package which includes an alkylpolyglycoside as one of the surfactants. In the manufacture of the solid block detergent composition, some surfactants and at least a part of the solidification matrix are blended at elevated temperatures. The anionic material is neutralized using an alkali metal and/or an alkaline earth metal base. The material is mixed until uniform and then combined with the balance of the ingredients. The warm liquid material is placed in a suitable container for solidification. Upon reaching ambient temperatures, the material hardens into a water soluble and dispersible solid block. For the purpose of this application, the term xe2x80x9csolidxe2x80x9d is different from a gel. Gels typically are a suspension of a solid material in a typically aqueous liquid material that at appropriate percentages form a thickened material or gelled material and have a measurable viscosity but no measurable penetrometer value (hardness). The materials of the present invention are solids in that they have a distinct solid character, have a measurable penetrometer value and melt at elevated temperatures. Preferred solids have a penetrometer value between about 3 and about 80; the lower the penetrometer value, the harder the solid block material. The solid block materials do not rely on a gelling mechanism in which water combines with solid materials to form a gel.
Accordingly, the invention is found in a detergent composition containing an effective detersive amount of a neutralized anionic surfactant; an alkali metal, an alkaline earth metal salt or a mixture thereof; an effective detersive amount of an alkyl polyglycoside surfactant; an effective detersive amount of a nonionic surfactant, an amphoteric surfactant or salt thereof, or a mixture thereof; and about 1 to 75 wt-% of a hardening agent, preferably about 3 to 75 wt-% of a polyethylene glycol; wherein the above components are dispersed to form a matrix which hardens to a solid block.
The invention is also found in a detergent composition which contains about 1 to 95 wt-% of a neutralized anionic surfactant including a mixed alkali metal alkaline earth metal salt of an organic sulfonate, an organic sulfate surfactant or mixture of such surfactants, an effective amount of an alkali or alkaline earth metal or mixture thereof; about 0.1 to 15 wt % of an alkyl polyglycoside; about 1 to 30 wt % of a nonionic foam stabilizing surfactant; and optionally about 0.1 to 10 wt % of an amphoteric surfactant.
The invention is further found in a solid block detergent composition as above defined which, when diluted with water, forms an aqueous detergent with stable foam and improved greasy soil removing capacity. The solid block detergent is useful in cleaning pots and pans, especially in manually washing pots and pans.
The solid block compositions are produced using a batch or continuous mixing system, preferably a single- or twin-screw extruder, by combining and mixing one or more cleaning agents and a hardening agent at high shear to form a homogeneous mixture. Preferably, the processing temperature is at or below the melting temperature of the ingredients. Optionally, but preferably, the cleaning agent is combined with one or more additive ingredients. The processed mixture may be dispensed from the mixer by extruding, casting or other suitable means, whereupon the composition hardens to a solid form which ranges in consistency from a solid block to a malleable, spongy, self-supporting form, such as a coil, square or other shape. Variations in processing parameters may be used to control the development of crystal size and crystalline structure of the matrix and thus the texture of the final product. For example, continuing to shear the mixture while solidification is in progress will create a smaller crystal and a pasty product. The structure of the matrix may be characterized according to hardness, melting point, material distribution, crystal structure, and other like properties according to known methods in the art. A cleaning composition processed according to the method of the invention is substantially homogeneous with regard to the distribution of ingredients throughout its mass, and is also substantially deformation-free.
The solid block detergents of the invention contain a package of surfactants including a neutralized anionic surfactant, either one or a mix of an alkali and alkaline earth metal salt and an alkylpolyglycoside. Nonionic and/or amphoteric surfactants may also form part of the package. The solid block detergent can be dispensed with a water spray to form an aqueous detergent for cutting and removing grease, removing and suspending soils and rinsing easily leaving cleaned ware. The aqueous detergent concentrate can be used in a cleaning liquid having exceptional soil, particularly grease removing properties with stable foam properties. The active ingredients and hardening agents, e.g. polyethylene glycol, are dispersed in a matrix which hardens to form a solid block.
Unless otherwise specified, the term xe2x80x9cwt-%xe2x80x9d is the weight of an ingredient based upon the total weight of the composition.
Cleaning Agents
The composition includes at least one cleaning agent which is a surfactant or surfactant system. This surfactant package has anionic surfactants, an alkyl polyglycoside and either a nonionic surfactant, an amphoteric surfactant or a mixture thereof. For a discussion of surfactants, see Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, volume 8, pages 900-912.
Anionic Surfactants
Anionic surfactants useful in the present cleaning compositions include, for example, sulfonates such as alkylsulfonates, alkylbenzenesulfonates, alkylarylsulfonates, sulfonated fatty acid esters, and the like; sulfates such as sulfated alcohols, sulfated alcohol ethoxylates, sulfated alkylphenols, alkylsulfates, sulfosuccinates, alkylether sulfates, and the like. Preferred anionics include an organic sulfonate surfactant or an organic sulfate surfactant. More preferred anionics include an alkylsulfonate, alkylarylsulfonate, sulfonated fatty acid ester, sulfated alcohol, sulfated alcohol ethoxylate, sulfated alkylphenol, alkyl sulfate, dialkylsulfosuccinate, alkylethersulfate, and mixtures thereof.
In the invention, the anionic surfactant(s) may be neutralized with an alkali metal salt and/or an alkaline earth salt or a mixture thereof. Preferably, a mixture of salts is used, and the alkali metal is sodium and the alkaline earth metal is magnesium. Preferably, the molar ratio of sodium to magnesium is from about 3:1 to 1:1, and, most preferably, the molar ratio of sodium to magnesium is about 2:1. Without wishing to be limited by theory, it is believed that the sodium cation serves to enhance solubility of the surfactant in water while the magnesium cation enhances solubility in oil.
Nonionic Surfactants
Nonionic surfactants useful in the present detergent compositions may include those having a polyalkylene oxide polymer as a portion of the surfactant molecule. Such nonionic surfactants include, for example, alcohol alkoxylates such as alcohol ethoxylate propoxylates, alcohol propoxylates, alcohol propoxylate ethyoxylate propoxylates, alcohol ethoxylate butoxylates, and the like, and alkyl-capped alcohol alkoxylates; polyoxyethylene glycol ethers of fatty alcohols such as CETEARETH(copyright)-27 or PARETH(copyright) 25-7, and the like; carboxylic acid esters such as glycerol esters, polyoxyethylene esters, ethoxylated and glycol esters of fatty acids, and the like; carboxylic amides such as diethanolamine condensates, monoalkanolamine condensates, polyoxyethylene fatty acid amides, and the like; and polyalkylene oxide block copolymers including an ethylene oxide/propylene oxide block copolymer such as those commercially available under the trademark PLURONIC(copyright) (BASF-Wyandotte), and the like; and other like nonionic compounds.
Preferably, the nonionic surfactant used is a polyhydroxy fatty acid amide. More preferably, the nonionic surfactant employed may be lauric monethanol amide. cocomonethanol amide, or a mixture thereof.
Alkyl Polyglycoside Surfactants
Alkyl polyglycosides are unusual in that they offer a hydrophilic portion which is based on sugar chemistry. The chemical structure is shown below, in which m generally ranges from 6 to 14 and n averages 1 or 2.
These surfactants have not been widely used to date due to a poor cost-performance profile. However, we have found that the use of such surfactants in the present solid block detergent composition provides benefits such as reducing skin irritation from the other surfactants, increasing foam stability and improving grease removal. The composition of the invention requires an alkyl polyglycoside which is preferably lauryl polyglycoside.
Amphoteric Surfactants
Also useful are amphoteric surfactants such as xcex2-N-alkylaminopropionic acids, N-Alkyl-xcex2-iminodipropionic acids, imidazoline carboxylates, N-alkylbetaines, sultaines, and the like. A preferred amphoteric surfactant is cocoamidopropylbetaine.
Aqueous Medium
The ingredients of the composition may be processed in a minor but effective amount of an aqueous medium such as water, to provide an effective level of viscosity for processing the mixture, and to provide the processed composition with the desired amount of firmness and cohesion during solid block formation and upon hardening. The mixture during processing may include about 0.01 to 15 wt-% of an aqueous medium, preferably about 0.1 to 10%t-%. The composition upon being discharged from the mixer may contain about 0.01 to 15 wt-% of an aqueous medium, preferably about 0.1 to 5 wt-%.
Hardening Agent
A hardening agent, as used in the present method and compositions, is a compound or system of compounds, organic or inorganic, that significantly contributes to the uniform solidification of the composition. Preferably, the hardening agents are compatible with the cleaning agent and other active ingredients of the composition, and are capable of providing an effective amount of hardness and/or aqueous solubility to the processed composition. The hardening agents should also be capable of forming a homogeneous matrix with the cleaning agent and other ingredients when mixed and solidified to provide a uniform dissolution of the cleaning agent from the solid composition during use.
The amount of hardening agent included in the cleaning composition will vary according to the type of cleaning composition being prepared, the ingredients of the composition, the intended use of the composition, the quantity of dispensing solution applied to the solid composition over time during use, the temperature of the dispensing solution, the hardness of the dispensing solution, the physical size of the solid composition, the concentration of the other ingredients, the concentration of the cleaning agent in the composition, and other like factors. It is preferred that the amount of the hardening agent is effective to combine with the cleaning agent and other ingredients of the composition to form a homogeneous mixture under continuous mixing conditions and a temperature at or below the melting temperature of the hardening agent.
It is also preferred that the hardening agent form a matrix with the cleaning agent and other ingredients which will harden to a solid form under ambient temperatures of about 30 to 50xc2x0 C., preferably about 35 to 45xc2x0 C., after mixing ceases and the mixture is dispensed from the mixing system, within about 1 minute to about 3 hours, preferably about 2 minutes to about 2 hours, preferably about 5 minutes to about 1 hour. A minimal amount of heat from an external source may be applied to the mixture to facilitate processing of the mixture. It is preferred that the amount of the hardening agent included in the composition is effective to provide a hardness and desired rate of controlled solubility of the processed composition when placed in an aqueous medium to achieve a desired rate of dispensing the cleaning agent from the solidified composition during use.
The preferred organic hardening agent is a polyethylene glycol (PEG) compound for use in the above cleaning composition. The solidification rate of cleaning compositions comprising a polyethylene glycol hardening agent made according to the invention will vary, at least in part, according to the amount and the molecular weight of the polyethylene glycol added to the composition.
Polyethylene glycol compounds useful according to the invention include, for example, solid polyethylene glycols of the general formula H(OCH2xe2x80x94CH2)nOH, where n is greater than 15, more preferably about 30 to 1700. Solid polyethylene glycols which are useful are commercially available from Union Carbide under the name CARBOWAX. Typically, the polyethylene glycol is a solid in the form of a free-flowing powder or flakes, having a molecular weight of about 1000 to 100,000, preferably having a molecular weight of at least about 1450 to 20,000, more preferably between about 1450 to about 8000. The polyethylene glycol is present at a concentration of from about 1 to 75 wt-%, preferably about 3 to 15 wt-%. Suitable polyethylene glycol compounds useful according to the invention include, for example, PEG 1450 and PEG 8000 among others, with PEG 8000 being most preferred.
Preferred inorganic hardening agents are hydratable inorganic salts, such as sulfates, acetates, carbonates, and bicarbonates. The inorganic hardening agents are present at concentrations of about 0 to 50 wt-%, preferably about 5-25 wt-%, more preferably about 5-15 wt-%.
Additive Agents
The cleaning compositions may further include conventional detergent adjuvants such as a sequestering agent, bleaching agent, alkaline source, enzyme, secondary hardening agent, detergent filler, defoamer, anti-redeposition agent, a threshold agent or system, aesthetic enhancing agent (i.e., dye, perfume), and other like additives. Adjuvants and other additive ingredients will vary according to the type of composition being manufactured.
Chelating/Sequestering Agents
The composition may include a chelating/sequestering agent such as an aminocarboxylic acid, a condensed phosphate, a phosphonate, a polyacry-late, and the like. In general, a chelating agent is a molecule capable of coordinating (i.e., binding) the metal ions commonly found in natural water to prevent the metal ions from interfering with the action of the other detersive ingredients of a cleaning composition. Depending on the type of cleaning composition being formulated, a chelating/sequestering agent is included in an amount of about 0.1 to 70 wt-%, preferably from about 5 to 50 wt-%.
Useful aminocarboxylic acids include, for example, n-hydroxyethyliminodiacetic acid, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), N-hydroxyethyl-ethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), and the like. Examples of condensed phosphates useful in the present composition include, for example, sodium and potassium orthophosphate, sodium and potassium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, and the like. A condensed phosphate may also assist, to a limited extent, in solidification of the composition by fixing the free water present in the composition as water of hydration.
The composition may include a phosphonate such as aminotris(methylene phosphonic acid), hydroxyethylidene diphosphonic acid, ethylenediaminetetra(methylene phosphonic acid), diethylenetriaminepente(methylene phosphonic acid), and the like. It is preferred to use a neutralized or alkaline phosphonate, or to combine the phosphonate with an alkali source prior to being added into the mixture such that there is little or no heat generated by a neutralization reaction when the phosphate is added.
Polyacrylates suitable for use as cleaning agents include, for example, polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymers, hydrolyzed polyacrylamide, hydrolyzed polymethacrylamide, hydrolyzed polyamide-methacrylamide copolymers, hydrolyzed polyacrylonitrile, hydrolyzed polymethacrylonitrile, hydrolyzed acrylonitrile-methacrylonitrile copolymers, and the like. For a further discussion of chelating agents/sequestrants, see Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, volume 5, pages 339-366 and volume 23, pages 319-320, the disclosure of which is incorporated by reference herein.
Bleaching Agents
Bleaching agents that may be used in a cleaning composition for lightening or whitening a substrate, include bleaching compounds capable of liberating an active halogen species, such as xe2x80x94Cl, xe2x80x94Br, xe2x80x94OCI and/or xe2x80x94Obr, under conditions typically encountered during the cleansing process. Suitable bleaching agents for use in the present cleaning compositions include, for example, chlorine-containing compounds such as a chlorine, hypochlorite, chloramine, and the like. Preferred halogen-releasing compounds include the alkali metal dichloroisocyanurates, chlorinated trisodium phosphate, the alkali metal hypochlorides, monochloramine and dichloramine, and the like. Encapsulated chlorine sources may also be used to enhance the stability of the chlorine source in the composition (see, for example, U.S. Pat. No. 4,618,914, the disclosure of which is incorporated by reference herein). A bleaching agent may also be a peroxygen or active oxygen source such as hydrogen peroxide, perborates, sodium carbonate peroxyhydrate, phosphate peroxyhydrates, potassium permonosulfate, and sodium perborate mono and tetrahydrate, with and without activators such as tetraacetylethylene diamine, and the like. A cleaning composition may include a minor but effective amount of a bleaching agent, preferably about 0.1 to 10 wt-%, preferably about 1 to 6 wt-%.
Alkaline Sources
The cleaning composition produced according to the invention may include minor but effective amounts of one or more alkaline sources to neutralize the anionic surfactants and improve soil removal performance of the composition. Accordingly, an alkali metal or alkaline earth metal hydroxide or other hydratable alkaline source, is preferably included in the cleaning composition in an amount effective to neutralize the anionic surfactant. However, it can be appreciated that an alkali metal hydroxide or other alkaline source can assist to a limited extent, in solidification of the composition. Although the amount of alkali metal and alkaline earth metal hydroxide is necessitated to neutralize the anionic surfactant as above described, additional alkaline sources may be present to a point where the pH of an aqueous solution does not exceed 9.
Suitable alkali metal hydroxides include, for example, sodium or potassium hydroxide. Suitable alkaline earth metal hydroxides include, for example, magnesium hydroxide. An alkali or alkaline earth metal hydroxide may be added to the composition in the form of solid beads, dissolved in an aqueous solution, or a combination thereof. Alkali and alkaline earth metal hydroxides are commercially available as a solid in the form of prilled beads having a mix of particle sizes ranging from about 12-100 U.S. mesh, or as an aqueous solution, as for example, as a 50 wt-% and a 73 wt-% solution. It is preferred that the alkali or alkaline earth metal hydroxide is added in the form of an aqueous solution, preferably a 50 wt-% hydroxide solution, to reduce the amount of heat generated in the composition due to hydration of the solid alkali material.
A cleaning composition may include a secondary alkaline source other than an alkali metal hydroxide. Examples of secondary alkaline sources include a metal silicate such as sodium or potassium silicate or metasilicate, a metal carbonate such as sodium or potassium carbonate, bicarbonate or sesquicarbonate, and the like; a metal borate such as sodium or potassium borate, and the like; ethanolamines and amines; and other like alkaline sources. Secondary alkalinity agents are commonly available in either aqueous or powdered form, either of which is useful in formulating the present cleaning compositions.
Detergent Fillers
A cleaning composition may include a minor but effective amount of one or more of a detergent filler, which does not perform as a cleaning agent per se, but cooperates with the cleaning agent to enhance the overall cleaning action of the composition. Examples of fillers suitable for use in the present cleaning compositions include sodium sulfate, sodium chloride, starch, sugars, and C1-C10 alkylene glycols such as propylene glycol, and the like. Preferably, the filler is included in an amount of about 1 to 20 wt-%, preferably about 3 to 15 wt-%.
Defoaming Agents
A minor but effective amount of a defoaming agent for reducing aeration during processing may also be included in a cleaning composition. Preferably, the cleaning composition includes about 0.0001 to 5 wt-% of a defoaming agent, preferably about 0.01 to 1 wt-%.
Examples of defoaming agents suitable for use in the present compositions include silicone compounds such as silica dispersed in polydimethylsiloxane, fatty amides, hydrocarbon waxes, fatty acids, fatty esters, fatty alcohols, fatty acid soaps, ethoxylates, mineral oils, polyethylene glycol esters, alkyl phosphate esters such as monostearyl phosphate, and the like. A discussion of defoaming agents may be found in U.S. Pat. No. 3,048,548 to Martin et al., U.S. Pat. No. 3,334,147 to Bruneile et al., and U.S. Pat. No. 3,442,242 to Rue et al., the disclosures of both references incorporated by reference herein.
Anti-Redeposition Agents
A cleaning composition may also include an anti-redeposition agent capable of facilitating sustained suspension of soils in a cleaning solution and preventing removed soils from being redeposited onto the substrate being cleaned. Examples of suitable anti-redeposition agents include fatty acid amides, fluorocarbon surfactants, complex phosphate esters, styrene maleic anhydride copolymers, and cellulosic derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and the like. A cleaning composition may include about 0.5 to 10 wt-%, preferably about 1 to 5 wt-%, of an anti-redeposition agent.
Dyes/Odorants
Various dyes, odorants including perfumes, and other aesthetic enhancing agents may also be included in the composition. Dyes may be included to alter the appearance of the composition, as for example, Direct Blue 86 (Miles), Fastusol Blue (Mobay Chemical Corp.). Acid Orange 7 (American Cyanamid), Basic Violet 10 (Sandoz). Acid Yellow 23 (GAF), Acid Yellow 17 (Sigma Chemical Co.), Fluorescein (Capitol Color and Chemical), Rhodamine (DandC Red No. 19), Sap Green (Keystone Analine and Chemical), Metanil Yellow (Keystone Analine and Chemical), Acid Blue 9 (Hilton Davis), Sandolan Blue/Acid Blue 182 (Sandoz), Hisol Fast Red (Capitol Color and Chemical), Acid Green 25 (Ciba-Geigy), and the like.
Fragrances or perfumes that may be included in the compositions include, for example, terpenoids such as citronellol, aldehydes such as amyl cinnamaldehyde, a jasmine such as CIS-jasmine or jasmal, vanillin, and the like.
Processing of the Composition
The invention provides a method of processing non-caustic cleaning compositions at lower temperatures and higher viscosities than are typically used when processing the same or similar composition by other methods such as a molten process.
Although not intended to limit the scope of the invention, it is believed that, at least in part, the continuous mixing of the ingredients of the cleaning composition at high shear enables the composition to be processed at a significantly lower temperature than that needed in other processing methods by which the ingredients of the composition are melted to form a homogeneous mixture. It is also believed that the continuous mixing of the ingredients enables the amount of the hardening agent required for effective hardening of a composition to be substantially reduced from that typically needed for preparing the corresponding cleaning compound by a molten process or other known method.
The mixing system provides for continuous mixing of the ingredients at high shear to form a substantially homogeneous semi-solid mixture in which the ingredients are distributed throughout the mass. The mixing system includes means for mixing the ingredients and to provide shear effective for maintaining the mixture at a flowable consistency such that the mixture can be stirred, mixed, agitated, blended, poured. extruded, and/or molded in conventional industrial mixing and/or shearing equipment of the type suitable for continuous processing and uniform distribution of ingredients in a mixture. Preferably, the viscosity of the mixture during processing is about 1,000 to 1,000,000 cps (about 1 to 1,000 Paxc2x7s), more preferably about 5,000 to 200,000 cps (about 5 to 200 Paxc2x7s). The mixing system is preferably a continuous flow mixer, as for example, a Teledyne continuous processor, a Beardsley Piper continuous mixer, more preferably a single- or twin-screw extruder, with a twin-screw extruder being highly preferred, as for example, a multiple section Buhler Miag twin-screw extruder.
Generally, the mixture is processed at a temperature lower than the melting temperature of the ingredients of the composition, preferably about 1 to 90xc2x0 C. lower, preferably about 5 to 20xc2x0 C. lower. Although minimal or no external heat may be applied to the mixture during processing, it can be appreciated that the temperature achieved by the mixture may become elevated during processing due to variances in processing conditions, and/or by an exothermic reaction between ingredients. Optionally, the temperature of the mixture may be increased, for example at the inlets or outlets of the mixing system, by applying heat from an external source to achieve a temperature of about 50 to 150xc2x0 C., preferably about 55 to 70xc2x0 C., to facilitate processing of the mixture.
In general, the composition is processed at a pressure of about 5 to 150 psig (about 34 to 1034 kPa), preferably about 10 to 30 psig (about 70 to 210 kPa). The pressure may be increased up to about 30 to 6000 psig (about 210 kPa to 41 MPa) to maintain fluidity of the mixture during processing, to provide a force effective to urge the mixture through the mixer and discharge port, and the like.
An ingredient may be in the form of a liquid or solid such as a dry particulate, and may be added to the mixture separately or as part of a premix with one or more other ingredient, as for example, the cleaning agent, aqueous medium, and additional ingredients such as a second cleaning agent, a detergent adjuvant or other additive, a hardening agent, and the like. One or more premixes may be added to the mixture.
An aqueous medium may be included in the mixture as desired, in a minor but effective amount to maintain the mixture at a desired viscosity during processing, and to provide the processed composition and final product with the desired amount of firmness and cohesion during discharge and hardening. The aqueous medium may be included in the mixture as a separate ingredient, or as part of a liquid ingredient or premix.
The ingredients are mixed together at high shear to form a substantially homogenous consistency wherein the ingredients are distributed substantially evenly throughout the mass. The mixture is then discharged from the mixing system by casting into a mold or other container or by extruding the mixture. Preferably, the mixture is cast or extruded into a mold or other packaging system, that can optionally, but preferably, be used as a dispenser for the composition. It is preferred that the temperature of the mixture when discharged from the mixing system is sufficiently low to enable the mixture to be cast or extruded directly into a packaging system without first cooling the mixture. Preferably, the mixture at the point of discharge is at about ambient temperature, about 30 to 50xc2x0 C. preferably about 35 to 45xc2x0 C. The composition is then allowed to harden to a solid form that may range from a low density, sponge-like, malleable, caulky consistency to a high density, fused solid, concrete-like block.
In a preferred method according to the invention, the mixing system is a twin-screw extruder which houses two adjacent parallel rotating screws designed to co-rotate and intermesh, the extruder having multiple barrel sections and a discharge port through which the mixture is extruded. The extruder may include, for example, one or more feed or conveying sections for receiving and moving the ingredients, a compression section, mixing sections with varying temperature, pressure and shear, a die section, and the like. Suitable twin-screw extruders can be obtained commercially and include for example, Buhler Miag Model No. 62 mm, Buhler Miag, Plymouth, Minn. USA.
Extrusion conditions such as screw configuration, screw pitch, screw speed, temperature and pressure of the barrel sections, shear, throughput rate of the mixture, water content, die hole diameter, ingredient feed rate, and the like, may be varied as desired in a barrel section to achieve effective processing of ingredients to form a substantially homogeneous liquid or semi-solid mixture in which the ingredients are distributed evenly throughout.
The extruder has a high shear screw configuration and screw conditions such as pitch, flight (forward or reverse) and speed effective to achieve high shear processing of the ingredients to a homogenous mixture. Preferably, the screw includes a series of elements for conveying, mixing, kneading, compressing, discharging, and the like, arranged to mix the ingredients at high shear and convey the mixture through the extruder by the action of the screw within the barrel section. The screw element may be a conveyor-type screw, a paddle design, a metering screw, and the like. A preferred screw speed is about 20 to 300 rpm, more preferably about 40 to 150 rpm.
Optionally, heating and cooling devices may be mounted adjacent the extruder to apply or remove heat in order to obtain a desired temperature profile in the extruder. For example, an external source of heat may be applied to one or more barrel sections of the extruder, such as the ingredient inlet section, the final outlet section, and the like, to increase fluidity of the mixture during processing through a section or from one section to another, or at the final barrel section through the discharge port. Preferably, the temperature of the mixture during processing including at the discharge port, is maintained at or below the melting temperature of the ingredients, preferably at about 50 to 200xc2x0 C.
In the extruder, the action of the rotating screw or screws will mix the ingredients and force the mixture through the sections of the extruder with considerable pressure. Pressure may be increased up to about 6,000 psig (about 41 MPa), preferably up to about 5 to 150 psig (about 34 to 1034 kPa), in one or more barrel sections to maintain the mixture at a desired viscosity level or at the die to facilitate discharge of the mixture from the extruder.
The flow rate of the mixture through the extruder will vary according to the type of machine used. In general, a flow rate is maintained to achieve a residence time of the mixture within the extruder effective to provide substantially complete mixing of the ingredients to a homogenous mixture, and to maintain the mixture at a fluid consistency effective for continuous mixing and eventual extrusion from the mixture without premature hardening.
When processing of the ingredients is complete, the mixture may be discharged from the extruder through the discharge port, preferably a die. The pressure may also be increased at the discharge port to facilitate extrusion of the mixture, to alter the appearance of the extrudate, for example, to expand it, to make it smoother or grainier in texture as desired, and the like.
The cast or extruded composition eventually hardens due, at least in part, to cooling and/or the chemical reaction of the ingredients. The solidification process may last from a few minutes to about 2 to 3 hours, depending, for example, on the size of the cast or extruded composition, the ingredients of the composition, the temperature of the composition, and other like factors. Preferably, the cast or extruded composition xe2x80x9csets upxe2x80x9d or begins to harden to a solid form within 30 seconds to about 3 hours, more preferably within about 1 minute to about 2 hours and most preferably within about 1 minute to about 1 hour.
Packaging System
The processed compositions of the invention may be cast or extruded into temporary molds from which the solidified compositions may be removed and transferred for packaging. The compositions may also be cast or extruded directly into a packaging receptacle. Extruded material may also be cut to a desired size and packaged, or stored and packaged at a later time.
The packaging receptacle or container may be rigid or flexible, and composed of any material suitable for containing the compositions produced according to the invention, as for example, glass, steel, plastic, cardboard, cardboard composites, paper, and the like. A preferred receptacle is a container made of a polyolefin such as polyethylene.
Advantageously, since the composition is processed at or near ambient temperatures, the temperature of the processed mixture is low enough so that the mixture may be cast or extruded directly into the container or other packaging receptacle without structurally damaging the receptacle material. As a result, a wider variety of materials may be used to manufacture the container than those used for compositions that processed and dispensed under molten conditions.
It is highly preferred that the packaging used to contain the compositions is manufactured from a material which is biodegradable and/or water-soluble during use. Such packaging is useful for providing controlled release and dispensing of the contained cleaning composition. Biodegradable materials useful for packaging the compositions of the invention include, for example, water-soluble polymeric films comprising polyvinyl alcohol, as disclosed for example in U.S. Pat. No. 4,474,976 to Yang; U.S. Pat. No. 4,692,494 to Sonenstein; U.S. Pat. No. 4,608,187 to Chang; U.S. Pat. No. 4,416,793 to Haq; U.S. Pat. No. 4,348,293 to Clarke; U.S. Pat. No. 4,289,815 to Lee: and U.S. Pat. No. 3,695,989 to Albert, the disclosures of which are incorporated by reference herein.
In addition, the mixture may be cast into a variety of shapes and sizes by extrusion since the viscosity of the mixture can be varied, for example, according to the amount of shear applied during mixing, the amount of hardening agent and water in the composition ingredients, temperature of the mixture, and other like factors. Also, unlike the xe2x80x9cmolten process.xe2x80x9d since the mixture is processed at a relatively low temperature, minimal cooling of the composition is required prior to or after casting or extruding. The low temperature of the discharged material also enhances safety for those handling the material. In addition, the extruded or cast composition will harden substantially simultaneously throughout its mass when the mixture is discharged from the mixing system due to cooling and/or the chemical reaction of the ingredients of the composition, with or without a hardening agent.
Dispensing of the Processed Compositions
It is preferred that a solid block cleaning composition made according to the present invention is dispensed from a spray-type dispenser such as those disclosed in U.S. Pat. Nos. 4,826,661, 4,690,305, 4,687,121, and 4,426,362, the disclosures of which are incorporated by reference herein. Briefly, a spray-type dispenser functions by impinging a water spray upon an exposed surface of the solid composition to dissolve a portion of the composition, and then immediately directing the concentrate solution comprising the composition out of the dispenser to a storage reservoir or directly to a point of use.
Compositions
The table below gives useful, preferred and more preferred composition ranges for each essential ingredient in the invention:
The invention is illustrated further by, but is not intended to be limited to, the following examples.
General Method of Preparation
The formulations described below were generally prepared by mixing the ingredients in a high shear mixer, preferably an extruder, as described here:
The high melt point solids, amides and polyethylene glycol, are melted in a tank. Then the liquid surfactant, sodium or magnesium laurel ether sulfate, is added followed by fragrance and dye. The premix is then held at 15 to 30xc2x0 F. (8 to 17xc2x0 C.) above its melt point. The solid surfactants, other solid ingredients and the liquid premix are simultaneously metered into the extruder. The product exits the extruder as a solid and is cut and transported to the packaging equipment.
Manual Foam Height Test Method
Purpose:
To screen hand dish washing detergents for foam height and stability.
Equipment Setup:
Calibrate the Guwina-Hofmann rotation device to 30 rpm.
Procedure:
Forty milliliters of the aqueous test solution is placed in a 250 ml stoppered graduated cylinder and warmed to 110xc2x0 F. (about 43xc2x0 C.). The cylinder is rotated for 4 minutes by a Guwina-Hofmann rotation device and an initial foam height is measured in ml gradients. Two drops (approximately 0.05 g) of a liquefied soil containing 45% shortening, 30% flour, 15% powdered egg and 10% oleic acid is added to the test solution, which is rotated for two minutes. This step is repeated until 45 ml or less foam results. The initial foam height, and the foam height after each addition of soil are summed to obtain a total foam height for the test. Each test is performed in triplicate, with an average foam height used to judge performance.
Grease Removal Test Procedure
Purpose:
To screen a detergent""s ability to remove grease.
Equipment Setup:
1. The lightning rod mixers need to be calibrated to 210 rpm. The rpm are determined with a digital readout tachometer.
2. The blade of the mixer should be centered on the 250 ml line of the beaker.
Calculations:       %              xe2x80x83            Removal    =            Soil                    xe2x80x83                  Removed      xc3x97      100              Total                    xe2x80x83                  Soil
Procedure:
Fifteen grams of clarified soil containing 82% corn oil, 13.5% hydrogenated soybean oil and 4.5% glycerol stearate is heated to 160xc2x0 F. (about 71xc2x0 C.) and is applied to 1000 ml polypropylene beakers which are then immersed in an ice bath. The soil solidifies and is held in the bath for five minutes. The soiled beaker is then stored at room temperature for 24 hours before performing the soil removal test. A test solution (500 ml) is heated to 110xc2x0 F. (about 43xc2x0 C.) and is added to a soiled beaker with constant stirring for 15 minutes. The beaker is drained, held overnight in an inverted position and is reweighed. Data recorded includes the hardness of the water used to make test solutions, the pH of the test solutions and the weight of soil removed. A commercially available hand dish washing detergent can be used a control.


An x-ray catheter has an x-ray tube having an x-ray source therein and an x-ray transparent window through which x-rays may pass is positioned with retractable needles or suction. The needles, if present, are retractably attached to a hinge which is operatively connected to a control that extends or retracts the needles from the device, the needles positioned adjacent the x-ray transparent window so as not to impede the flow of x-rays. Alternatively, suction opening operatively connected to a vacuum source positions the x-ray source at the desired site.

The invention relates to a miniaturized x-ray having a x-ray source catheter that generates x-rays while minimizing risk of exposure to the x-rays. Retractable needles are provided to anchor the x-ray source at a desired site or to deliver therapeutic or diagnostic agents.
Traditionally, x-rays have been used in the medical industry to view bone, tissue and teeth. X-rays have also been used to treat cancerous and precancerous conditions by exposing a patient to x-rays using an external x-ray source. Treatment of cancer with x-rays presents many well documented side effects, many of which are due to the broad exposure of the patient to the therapeutic x-rays.
Minimally invasive endoscopic techniques have been developed and are used to treat a variety of conditions. Endoluminal procedures are procedures performed with an endoscope, a tubular device into a lumen of which may be inserted a variety of rigid or flexible tools to treat or diagnose a patient""s condition. Endoscopes can be either rigid or flexible, and are chosen according to the desired application.
The desire for improved minimally invasive medical devices and techniques have led to the development of miniaturized x-ray devices that may be used in the treatment or prevention of a variety of medical conditions. International Publication No. WO 98/48899 describes a miniature x-ray unit having an anode and cathode separated by a vacuum gap positioned inside a metal housing. The anode includes abase portion and a projecting portion. The x-ray unit is insulated and connected to a coaxial cable which, in turn, is connected to the power source. An x-ray window surrounds the projecting portion of the anode and the cathode so that the x-rays can exit the unit. The x-ray unit is sized for intra-vascular insertion, and may be used, inter alia, in vascular brachytherapy of coronary arteries, particularly after balloon angioplasty.
International Publication No. WO 97/07740 describes an x-ray catheter having a catheter shaft with an x-ray unit attached to the distal end of the catheter shaft. The x-ray unit comprises an anode and a cathode coupled to an insulator to define a vacuum chamber. The x-ray unit is coupled to a voltage source via a coaxial cable. The x-ray unit can have a diameter of less than 4 mm and a length of less than about 15 mm, and can be used in conjunction with coronary angioplasty to prevent restenosis.
U.S. Pat. No. 5,795,339 describes a catheter-advancement actuated needle retraction system is disclosed herein. The invention includes a generally hollow barrel that houses a needle hub, which can include a flashback chamber. A needle is affixed to the distal end of the needle hub and is aligned to extend through an opening in the distal end of the barrel. The needle extends through a catheter hub and catheter affixed to the catheter hub. A spring is disposed in the barrel lumen to cooperate with the needle hub to urge the needle hub toward the proximal end of the barrel. A latch actuator is releasably engaged with the catheter hub. A latch, which cooperates with the latch actuator, is movable between one position, which maintains the needle hub adjacent to the distal end of the barrel, and a second position allowing the spring to urge the needle hub to the proximal end of the barrel. A mechanism may be provided to cushion the needle hub as it contacts the proximal end of the barrel by the force of the spring.
U.S. Pat. No. 5,865,806 describes a one step catheter advancement automatic needle retraction system. It comprises a generally hollow barrel, a needle hub which can include a flashback chamber disposed in the barrel, a secondary flashback chamber disposed in the barrel, a biasing mechanism for retracting the needle into the barrel and a clip associated with the secondary flashback chamber for engaging a catheter hub. The needle hub in conjunction with the secondary flashback chamber retains the needle in the extended position against the force of the biasing mechanism until the catheter has been advanced a certain distance from the distal end of the barrel.
U. S. Pat. No. 5,718,688 describes a catheter placement unit comprising a catheter having an axial bore, a catheter hub at one end of the catheter, an introducing needle having a pointed tip for introducing the catheter into a desired position in a patient""s body, and a needle hub on the needle remote from the tip for mounting the needle so that it extends through the catheter bore for introduction of the catheter into the patient""s body and so that it can subsequently be withdrawn from the catheter bore leaving the catheter in position in the patient""s body. The unit includes a needle tip protector on the needle for shielding the needle tip when the needle has been withdrawn from the catheter bore. The needle tip protector includes a locking device which is initially in an unlocked position permitting withdrawal of the needle from the catheter bore but which is arranged to be placed in a locked position, in which the locking device engages the outer surface of the needle, by withdrawal of the needle from the catheter bore so as to lock the needle tip protector on the needle in the shielding position. The locking device retains the catheter hub on the needle when the locking device is in the unlocked position and releases the catheter hub from the needle when the locking device is in the locked position. Separation of the catheter from the needle is therefore prevented until the needle has been drawn from the catheter bore to trigger shielding of the needle tip.
U.S. Pat. No. 5,704,914 describes a catheter assembly is which includes a flexible catheter, a hub attached to the catheter which defines a lumen and an adjoining flash back chamber which communicate with the catheter, and a flexible resilient diaphragm attached to the hub through which a hypodermic needle such as a catheter introducer needle can be passed. The diaphragm prevents a liquid, such as blood, which has been introduced into the hub lumen from flowing past the diaphragm and beyond the hub when the diaphragm is unpenetrated. A hollow tubular body may also be included to which a cannulated catheter needle can be either stationarily or movably attached. The body is removably attached to the hub behind the diaphragm. If movably attached to the body, the needle has a retracted position fully recessed within the body for safe storage and an advanced operative position extending through the diaphragm, hub and catheter. A needle occluding member may also be provided to prevent a liquid such as blood from flowing through the needle into the body. The member may be a movable guide wire or a stationary obturator member. A liquid outlet port can be provided on the side of the hub and a multi-position stop cock can be mounted on the hub to direct liquid flow from the catheter to the side port while blocking flow toward the diaphragm and vise versa.
U.S. Pat. No. 5,782,740 describes a rapid exchange type intravascular catheter suitable for maintaining patency of a body lumen for a period of time sufficient to permit delivery of a radiation source to the body lumen. The catheter utilizes a reinforcing mandrel to improve the pushability and strength of the catheter as it tracks along a guide wire, and permits blood flow through an inflatable member while radiation therapy is being provided.
U.S. Pat. No. 5,816,999 describes the provision of ionizing radiation from an extracorporeal source to the interior of an internal body cavity or lumen and the dispersion of this radiation across a desired area of diseased tissue. It consists of an extracorporeal radiation source, a flexible catheter containing at least one hollow conduit for the transportation of the radiation along a curved path, an entrance portion to the catheter for the capture of the radiation, and an x-ray dispersive closure cap at the distal end of the catheter for the dispersion of the radiation within the body cavity or lumen and onto a specific area of tissue. It can be used to destroy cancerous regions within the body, such as in the pulmonary system, as well for applications in the vasculature and other internal regions of the living body.
U.S. Pat. No. 5,566,221 describes a kit for delivering x-rays to the interior surface of a body cavity. The kit includes an x-ray source and an x-ray source guidance tube. The guidance tube includes an inflatable inelastic balloon disposed about and affixed at its distal end such that when inflated, the central axis of the balloon is coaxial with and is disposed about the central axis of the tubular element Inflation and deflation of the balloon is controllable from the proximal end of the tubular element. The x-ray source may include an electron-activated target for generating x-rays in response to electrons incident on the target. The x-ray source may also include means for generating an electron beam and steering the beam so that it is incident on the target. The target end is slidably positionable within an interior channel of the source guidance tube.
U.S. Pat. No. 5,562,633 describes a catheter placement unit having an introducing needle having a pointed tip for introducing a catheter into a desired position in a patient""s body, a needle hub for mounting the needle so that the needle extends through an axial bore in the catheter during introduction of the catheter into the patient""s body and so that the needle can subsequently be withdrawn from the catheter bore leaving the catheter in position in the patient""s body, and a needle tip protector on the needle for shielding the needle tip when the needle has been withdrawn from the catheter bore. The needle tip protector includes a guard element which is held against a resilient bias in a cocked position to one side of the catheter while the catheter is introduced into the patient""s body and which, on subsequent withdrawal of the needle from the catheter bore, is moved laterally by resilient action from the cocked position into a guard position in which it shields the needle tip. Thus the protector reliably guards against needle stick injuries during withdrawal and subsequent disposal of the needle.
U.S. Pat. No. 5,041,107 describes an implantable apparatus for continuous or periodic introduction of a drug to a desired release point in the body comprises an implantable power source and an elongated flexible plastic tubular catheter having a lumen filled with the drug to be delivered and containing therein a first device electrode. The distal end of the catheter is closed and located near the distal end is a port which extends through the wall of the catheter to communicate with the lumen. Just proximal of the port is a surface electrode mounted on the exterior wall of the catheter body. Extending through the catheter and joined to the drive electrode and the surface electrode are conductors which couple those electrodes to the implanted power source. Energization of the electrodes with a predetermined direct current potential causes a flow of the ionized drug molecules out through the port and into the area surrounding the surface electrode.
U.S. Pat. No. 5,599,346 describes a radio frequency (RF) treatment system includes first and second catheters with first and second needle electrodes positioned at least partially in lumens of the first and second catheters. Each electrode is surround by a insulator sleeve which is slideable along the electrode and defines an ablation surface. An RF power source is coupled to the first and second needle electrodes. The electrodes provide bipolar RF ablation between the two, defining an ablation volume. A deflectable introducer has a laterally deflectable distal end and an ablation volume temperature sensor positioned at the distal end. The deflectable introducer is advanced in and out of the electrodes distal ends to measure a temperature of tissue in the ablation volume. The treatment system can include more than two electrodes, such as two pairs of electrodes. Further, the system can include a needle electrode extension with a laterally deflectable distal end. The needle electrode extension is positioned in at least one of the distal ends of one of the needle electrodes. It is advanced in and out of the needle electrode distal end to provide monopolar ablation. Additionally, the RF treatment system provides for the introduction of an infusion media, including but not limited to a chemotherapeutic agent, through distribution ports in the needle electrodes, or through one or more infusion devices that can house the needle electrodes and their respective catheters.
One problem with all of the foregoing devices is anchoring the device to the desired site within a subject, in part due to a high degree of relative motion in living systems between an endoscope and the target organ, this relative motion increases the likelihood of improper positioning without a suitable endoscope anchoring system. Improper positioning can lead to ineffective therapy and undesirable side effects. The present invention provides an anchoring system that overcomes the problems of prior art devices.
The present invention also allows the penetration of x-rays to kill lesions that are located behind the surface of healthy tissue regions in the body or lesions that are partially thick or massive. This is a significant advantage of targeted minimally invasive therapy compared to externally applied radiation technique. For example, gastrointestinal lesions often begin on the internal lining (endotheliem) of the organ. Accordingly, treatment of such lesions with externally applied x-rays requires the application of higher power over a broad volume of healthy tissue between the skin and the lesion. However, positioning the x-ray source at the lesion advantageously achieves the same or higher power density at the site of the lesion while lowering the overall x-ray energy dissipated in healthy tissue.
The present invention relates to an x-ray catheter having an anchoring system made of retractable needles which secure the x-ray catheter into position on the target tissue, and can be optionally used to inject drugs into the patient, and to measure the distance between the x-ray source and the tumor.
This invention preferably provides a removable attachment to an x-ray catheter that contains a x-ray source. The anchoring or positioning system is formed as a metal shield that shields emissions of x-rays from the x-ray source. A set of needles is retractably affixed to the shield. These needles are affixed on rows on opposite sides of the x-ray source. A sleeve is provided wherein that the needles may be retractably sheathed adjacent to the x-ray source. Each needle of the multiple needle assembly is pivotally attached to the shield by a pin that allows the needle to move between a retracted position and an activated position. In the retracted position the needles can be safely pushed into and out of the body, and a sleeve is preferably provided over the needles for safety.
In the activated position, the needles extend into a position such that they are facing in the same, general direction as the desired site of irradiation. Control connects between the needles and the control system outside the patient, wherein, by manipulation of the control, the needles extend into their anchor position. In an alternative embodiment, suction can be used to engage the needles into the tissue.
The endoscope positions the needle system while the needles are extended. The endoscope is then used to embed the needles into the region by applying force. An inflatable balloon system may also be used to press the device into the tissue. The needles may be solid or hollow with infeed and exit openings.
Optionally, a therapeutic or diagnostic agent may optionally be delivered from a reservoir that communicates with the needles through hollow tubing. In this embodiment, the needles are hollow, but they may be solid if delivery of a therapeutic agent is not required. The needle can also be coated with a therapeutic or a diagnostic agent. In some instances, the needles can be retracted and in others they can be left in place if xe2x80x9cbreak awayxe2x80x9d needles are used. Addition of a score line on the needle at a proper position will break away when the proper force is applied.
The needles preferably have markings in them so that the vision system of the endoscope can determine the position and depth of the needles. This insures the proper x-ray dose and (b) can insure that therapeutic agents, when required, are delivered to the tumor region and not to healthy tissue.
In an alternative embodiment, the x-ray catheter include a housing having a suction opening and connected to a vacuum source, an x-ray catheter having an x-ray source therein and an x-ray transparent window adjacent the x-ray source. The x-ray catheter is placed inside the housing such that a space is formed therebetween, and the suction opening being in operative alignment with the x-ray transparent window such that x-ray may exit the window and the suction opening, the vacuum source crating suction at the suction opening to adhere the device to the desired site.

Miniature x-ray catheter with retractable needles or suction means for positioning at a desired site


This invention describes improved polishing pads useful in the manufacture of semiconductor devices or the like. The pads of the present invention have an advantageous hydrofoil polishing material and have an innovative surface topography and texture which generally improves predictability and polishing performance.

1. Field of the Invention
The present invention relates generally to polishing pads useful in the manufacture of semiconductor devices or the like. More particularly, the polishing pads of the present invention comprise an advantageous hydrofoil material having an innovative surface topography and texture which generally improves polishing performance (as well as the predictability of polishing performance).
2. Discussion of the Related Art
Integrated circuit fabrication generally requires polishing of one or more substrates, such as silicon, silicon dioxide, tungsten, copper or aluminum. Such polishing is generally accomplished, using a polishing pad in combination with a polishing fluid.
The semiconductor industry has a need for precision polishing to narrow tolerances, but unwanted xe2x80x9cpad to padxe2x80x9d variations in polishing performance are quite common. A need therefore exists in the semiconductor industry for polishing pads which exhibit more predicable performance during high precision polishing operations.
U.S. Pat. No. 5,569,062 describes a cutting means for abrading the surface of a polishing pad. U.S. Pat. No. 5,081,051 describes an elongated blade having a serrated edge pressing against a pad surface, thereby cutting circumferential grooves into the pad surface. U.S. Pat. No. 5,489,233 is directed to a polishing pad having large and small flow channels produced solely by external means upon the surface of a solid uniform polymer sheet.
The present invention is directed to polishing pads having an innovative hydrofoil polishing layer and also an innovative polishing surface topography and texture. xe2x80x9cTopographyxe2x80x9d is intended to mean surface characteristics on a scale of less than 10 microns, and xe2x80x9csurface texturexe2x80x9d is intended to mean surface characteristics of 10 microns or more.
The polishing pads of the present invention comprise a random surface topography. The random surface topography is preferably achieved by solidifying or otherwise forming (without cutting) the polishing surface, rather than cutting or skiving the pad from a larger material. Cutting or skiving causes a blade or other cutting implement to cut substantially parallel to the polishing surface being formed; such cutting tends to create a on-random surface topography, because as the blade cuts the polishing surface, it scores the surface or otherwise causes a pattern on the surface; this pattern generally indicates the direction of cutting.
It has been surprisingly discovered that for certain high precision polishing applications, a non-random surface pattern, due to cutting or skiving, tend to create a relatively high (and unpredictable) number of undesirable macro-defects. xe2x80x9cMacro-defectsxe2x80x9d are intended to mean burrs or other protrusions from the polishing surface of the pad which have a dimension (either width, height or length) of greater than 25 microns. Such macro-defects are detrimental to polishing and can cause performance variations between pads, because although the cutting process may be substantially the same for each pad, as the cutting instrument dulls, the amount of macro-defects created by the cutting instrument generally increases. Other factors which can cause variability in macro-defects during cutting include ambient temperature, and line speed variations.
Macro-defects should not be confused with xe2x80x9cmicro-asperities.xe2x80x9d Micro-asperities are intended to mean burrs or other protrusions from the polishing surface of the pad which have a dimension (either width, height or length) of less than 10 microns. It has been surprisingly discovered that micro-asperities are generally advantageous in precision polishing, particularly in the manufacture of semi-conductor devices.
The polishing materials of the present invention have no intrinsic ability to absorb or transport slurry particles, and therefore the present invention does not include felt-based polishing pads created by coalescing a polymer onto a fiber substrate, as described in U.S. Pat. No. 4,927,432 to Budinger, et al. Furthermore, the polishing materials of the present invention comprise a hydrofoil material having: i. a density greater than 0.5 g/cm3; ii. a critical surface tension greater than or equal to 34 milliNewtons per meter; iii. a tensile modulus of 0.02 to 5 GigaPascals; iv. a ratio of tensile modulus at 30xc2x0 C. to tensile modulus at 60xc2x0 C. of 1.0 to 2.5; v. a hardness of 25 to 80 Shore D; vi. a yield stress of 300-6000 psi (2.1-41.4 MegaPascal); vii. a tensile strength of 1000 to 15,000 psi (7-105 MegaPascal); and viii. an elongation to break up to 500%. In a preferred embodiment, the polishing layer further comprises a plurality of soft domains and hard domains.
The present invention is innovative, because: 1. it recognizes the detrimental effects of macro-defects for precision polishing, while also recognizing the benefits of micro-asperities; 2. the present invention also recognizes how macro-defects generally occur in polishing pads; and 3. the present invention teaches how to manufacture polishing pads having advantageously low levels of macro-defects but advantageously high levels of micro-asperities. None of these aspects of the present invention were heretofore appreciated in the art and are truly a significant contribution to the art of precision polishing. The pads of the present invention have a relatively low level of macro-defects, because the polishing surfaces are not created by cutting or skiving, but rather, are created by solidifying or otherwise forming the polishing surface without cutting. Preferably, the polishing surface of the pads of this invention has, on average, less than 2 observable macro-defects per square millimeter of polishing surface when viewed at a magnification of 1000X.
The polishing layers of the present invention are manufactured by: 1. molding, embossing, printing, casting, sintering, photo-imaging, chemical etching, solidifying or otherwise creating pads without cutting the pad from a larger material; and 2. applying at least a portion of a macro-texture onto (or into) the polishing surface without cutting (or similar-type fracturing of) the polishing surface. The method(s) of the present invention are directed to causing a flowable material to form (without cutting) a macro-textured into or onto a surface (and optionally also forming a micro-texture) or alternatively (or in addition) thereafter inducing a macro-texture upon the polishing surface without cutting or similar type fracturing of the polishing surface, such as, by embossing. Optionally, additional macro-texture (and/or micro-texture) can thereafter be machined or otherwise cut into the polishing surface.
The present invention is directed to an improved polishing pad useful in the polishing or planarizing of substrates, particularly substrates for the manufacture of semiconductor devices or the like. The compositions and methods of the present invention may also be useful in other industries and can be applied to any one of a number of materials, including but not limited to silicon, silicon dioxide, metal, dielectrics (including polymeric dielectrics), ceramics and glass.
Macro defects (large surface defects of 25 microns or more due to fractures, abrasions and/or similar-type surface irregularities, generally arising from the cutting of a macro-texture into a pad) must be distinguished from micro asperities (small surface protrusions of 10 microns or less due to surface fractures, abrasion and/or similar-type surface irregularities, generally arising from the cutting of a micro-texture into a pad). Macro-texture and micro-texture provide very different functions for a polishing pad. The macro-texture provides a passageway (or a series of passageways) for distributing polishing fluid along the pad surface. The micro-texture can be very similar to the macro-texture, but on a much smaller scale.
Unlike the (much larger) macro-texture, the micro-texture is on a scale similar to that of the surface protrusions being polished away. The micro-texture provides an environment which enhances interaction between: 1. the polishing fluid and/or polishing particles; and 2. the protrusions to be polished away.
The present invention is innovative in its recognition that: 1. micro-asperities are generally beneficial to the polishing performance of a pad; and 2. macro-defects are generally detrimental to polishing performance of a pad. The present invention is also innovative in addressing the adverse affects of macro-defectsxe2x80x94by solidifying or otherwise forming or molding at least a portion of the macro-texture into or onto the polishing surface, macro-defects are dramatically reduced and pad performance is improved, relative to conventional pads produced by cutting a macro-texture into a pad.
In conventional pad manufacturing processes, mechanical cutting operations are used:
1. to cut pads from a polymer cake; or
2. to cut or otherwise machine a macro-texture into a pad.
The number of macro-defects can be dependent upon the sharpness of the cutting tool, line speed, ambient temperature/humidity and the like. This will tend to cause pad-to-pad variation in macro-defects which in turn will cause pad-to-pad variation in polishing performance.
The pads of the present invention comprise a polishing layer having an outer surface. Preferred processes in accordance with the present invention include: 1. thermoplastic injection molding, 2. thermoset injection molding (often referred to as xe2x80x9creaction injection moldingxe2x80x9d or xe2x80x9cRIMxe2x80x9d), 3. thermoplastic or thermoset injection blow molding, 4. compression molding, or 5. any similar-type process in which a flowable material is positioned and solidified, thereby creating at least a portion of a pad""s macro-texture. In a preferred molding embodiment of the present invention: 1. the flowable material is forced into or onto a structure or substrate; 2. the structure or substrate imparts a surface texture into the material as it solidifies; and 3. the structure or substrate is thereafter separated from the solidified material.
In one embodiment, a solid or semi-solid insert is first placed in an enclosure, and the flowable material is then forced into the enclosure, thereby causing the insert to be bonded to or within the material after it has solidified. The insert can provide reinforcement to the pad so that the solidified material around the insert need not be self-supporting or otherwise of a consistency necessary to support the polishing layer. Alternatively or in addition, the insert can provide structural integrity to the pad, thereby providing improved performance, longevity and/or greater flexibility in manufacturing.
Machining a groove or indentation into a pad disrupts the pad""s surface, causing fracturing, abrasion, irregularities or otherwise macro-defects to the pad surface; in the precision polishing required in the semiconductor industry, such macro-defects (due to machining a macro-texture into a polishing pad) can be detrimental to pad performance (particularly predictability). By flowing and solidifying (e.g., molding) at least a portion of the macro-texture into (or onto) the pad polishing layer (without cutting) in accordance with the present invention, the polishing layer surface is far less disturbed or damaged (relative to machining); therefore the pads of the present invention will exhibit fewer macro-defects, and pad polishing performance and predictability of pad performance, are generally improved.
Although molding technology useful in accordance with the present invention is quite common in many industries, the molding of the present invention involves an average mold aspect ratio of at least 400, more preferably at least 500 and yet more preferably greater than 700. The xe2x80x9caspect ratioxe2x80x9d is intended to mean a selected length divided by the average thickness of the pad.
Molding a precision polishing pad with such a high aspect ratio is contrary to prevailing views in the industry and can be difficult, if not impossible, depending upon the pad material selected. As a result, polishing pads have been manufactured by other manufacturing operations, such as by coagulating polymer onto felt substrates or by casting a polymeric material into cakes (which are then skived to produce a polishing pad), because the advantages of the present invention have not been appreciated by those of ordinary skill in the art.
Surprisingly, the preferred compositions of the present invention can be molded in accordance with the present invention to provide polishing pads which are able to satisfy needs which are not otherwise obtainable with common prior art pad manufacturing processes. For example, the pads of the present invention are generally more precise and reproducible, relative to many conventional pad manufacturing processes.
Pads are generally conditioned prior to use. The conditioning creates or augments the micro-texture of the pad. During use, the micro-texture can experience unwanted plastic flow and can be fouled by debris. As a result, pads are generally re-conditioned periodically during their useful life to regenerate an optimal micro-texture. In some embodiments, the polishing pads of the present invention require less re-conditioning during use, relative to conventional polishing pads.
In a preferred embodiment, the pad""s macro-structure is incorporated into the surface of the polishing layer, due to the presence of mold protrusions around which pad material initially flows and solidifies. In this way, the macro-texture can be simultaneously created along the polishing layer""s outer surface as the pad material solidifies. The macro-texture preferably comprises one or more indentations having an average depth and/or width of greater than 0.01, more preferably 0.05 and yet more preferably 0.1 millimeters. This macro-texture facilitates the flow of polishing fluid and thereby enhances polishing performance.
A preferred process of the present invention is directed to injection molding, particularly xe2x80x9creaction injection moldingxe2x80x9d or xe2x80x9cRIMxe2x80x9d. RIM generally involves mixing reactive liquid (or semi-liquid) precursors which are then rapidly injected into the mold. Once the mold is filled, the reactive precursors proceed with a chemical reaction, causing solidification of a final molded product. This type of injection molding is most preferred, because the pad""s physical properties can be fine tuned by adjusting the reactive chemistry. In addition, reaction injection molding generally uses lower viscosity precursors than thermoplastic injection molding, thereby allowing for easier filling of high aspect ratio molds.
Urethane prepolymers are a preferred reactive chemistry for reaction injection molding in accordance with the present invention. xe2x80x9cPrepolymersxe2x80x9d are intended to mean any precursor to the final polymerized product, including oligomers or monomers. Many such prepolymers are well known and commercially available. Urethane prepolymers generally comprise reactive moieties at the ends of the prepolymer chains.
A common reactive moiety for a urethane prepolymer is isocyanate. Commercially available isocyanate prepolymers include di-isocyanate prepolymers and tri-isocyanate prepolymers. Examples of di-isocyanate polymers include toluene diisocyanate and methylene diisocyanate. The isocyanate prepolymer preferably comprises an average isocyanate functionality of at least two. An average isocyanate functionality greater than 4 is generally not preferred, since processing can become difficult, depending upon the molding equipment and process being used.
The isocyanate prepolymer is generally reacted to a second prepolymer having an isocyanate reactive moiety. Preferably, the second prepolymer comprises, on average, at least two (2) isocyanate reactive moieties. Isocyanate reactive moieties include amines, particularly primary and secondary amines, and polyols; preferred prepolymers include diamines, diols and hydroxy functionalized amines. In addition, abrasive particles may be incorporated into the pad material. De-watered polishing fluid or any precursor to a polishing fluid may be incorporated into the pad, whereby during polishing, as water is placed within the polishing interface and the pad wears, the pad provides constituents to create or improve the polishing fluid.
Any prepolymer chemistry however could be used in accordance with the present invention, including polymer systems other than urethanes, provided the final product exhibits the following properties: a density of greater than 0.5 g/cm, more preferably greater than 0.7 g/cm and yet more preferably greater than about 0.9 g/cm3; a critical surface tension greater than or equal to 34 milliNewtons per meter; a tensile modulus of 0.02 to 5 GigaPascals; a ratio of the tensile modulus at 30xc2x0C. to the modulus at 60xc2x0 C. in the range of 1.0 to 2.5; hardness of 25 to 80 Shore D; a yield stress of 300 to 6000 psi; a tensile strength of 500 to 15,000 psi, and an elongation to break up to 500%. These properties are possible for a number of materials useful in injection molding and similar-type processes, such as: polycarbonate, polysulphone, nylon, ethylene copolymers, polyethers, polyesters, polyether-polyester copolymers, acrylic polymers, polymethyl methacrylate, polyvinyl chloride, polycarbonate, polyethylene copolymers, polyethylene imine, polyurethanes, polyether sulfone, polyether imide, polyketones, and the like, including photochemical reactive derivatives thereof.
A catalyst is often necessary to decrease the polymerization reaction time, particularly the gel time and the de-mold time. However, if the reaction is too fast, the material may solidify or gel prior to complete filling of the mold. Gel time is preferably in the range of a half second and one hour, more preferably in the range of about 1 second and about 5 minutes, more preferably 10 seconds to 5 minutes, and yet more preferably 30 seconds to 5 minutes.
Preferred catalysts are devoid of transition metals, particularly zinc, copper, nickel, cobalt, tungsten, chromium, manganese, iron, tin, or lead. The most preferred catalyst for use with a urethane prepolymer system comprises a tertiary amine, such as, diazo-bicyclo-octane. Other useful catalysts include, organic acids, primary amines and secondary amines, depending upon the particular reactive chemistry chosen.
In a preferred embodiment, the pad material is sufficiently hydrofoil to provide a critical surface tension greater than or equal to 34 milliNewtons per meter, more preferably greater than or equal to 37 and most preferably greater than or equal to 40 milliNewtons per meter. Critical surface tension defines the wettability of a solid surface by noting the lowest surface tension a liquid can have and still exhibit a contact angle greater than zero degrees on that solid. Thus, polymers with higher critical surface tensions are more readily wet and are therefore more hydrofoil. Critical Surface Tension of common polymers are provided below:
In one embodiment, the pad matrix is derived from at least:
1. an acrylated urethane;
2. an acrylated epoxy;
3. an ethylenically unsaturated organic compound having a carboxyl, benzyl, or amide functionality;
4. an aminoplast derivative having a pendant unsaturated carbonyl group;
5. an isocyanurate derivative having at least one pendant acrylate group;
6. a vinyl ether,
7. a urethane
8. a polyacrylamide
9. an ethylene/ester copolymer or an acid derivative thereof;
10. a polyvinyl alcohol;
11. a polymethyl methacrylate;
12. a polysulfone;
13. an polyamide;
14. a polycarbonate;
15. a polyvinyl chloride;
16. an epoxy;
17. a copolymer of the above; or
18. a combination thereof.
Preferred pad materials comprise urethane, carbonate, amide, sulfone, vinyl chloride, acrylate, methacrylate, vinyl alcohol, ester or acrylamide moieties. The pad material can be porous or non-porous. In one embodiment, the matrix is non-porous; in another embodiment, the matrix is non-porous and free of fiber reinforcement.
In a preferred embodiment, the polishing layer material comprises:
1. a plurality of rigid domains which resists plastic flow during polishing; and
2. a plurality of less rigid domains which are less resistant to plastic flow during polishing. This combination of properties provides a dual mechanism which has been found to be particularly advantageous in the polishing of silicon dioxide and metal. The hard domains tend to cause the protrusion to rigorously engage the polishing interface, whereas the soft domains tend to enhance polishing interaction between the protrusion and the substrate surface being polished.
The rigid phase size in any dimension (height, width or length) is preferably less than 100 microns, more preferably less than 50 microns, yet more preferably less than 25 microns and most preferably less than 10 microns. Similarly the non-rigid phase is also preferably less than 100 microns, more preferably less than 50 microns, more preferably less than 25 microns and most preferably less than 10 microns. Preferred dual phase materials include polyurethane polymers having a soft segment (which provides the non-rigid phase) and a hard segment (which provides the rigid phase). The domains are produced during the forming of the polishing layer by a phase separation, due to incompatibility between the two (hard and soft) polymer segments.
Other polymers having hard and soft segments could also be appropriate, including ethylene copolymers, copolyester, block copolymers, polysulfones copolymers and acrylic copolymers. Hard and soft domains within the pad material can also be created: 1. by hard and soft segments along a polymer backbone; 2. by crystalline regions and non-crystalline regions within the pad material; 3. by alloying a hard polymer with a soft polymer; or 4. by combining a polymer with an organic or inorganic filler. Useful such compositions include copolymers, polymer blends interpenetrating polymer networks and the like.
The pads of the present invention are preferably side-filled by injecting the pad material into the mold at a point along the periphery of the mold. Pads may also be center filled by injecting flowable material into the mold at or near the geometric center of a mold face.
A preferred method of creating the macro-channels or macro-indentations is by molding, particularly injection molding, whereby the macro-texture is formed in situ by one or more thin-walled protrusions extending into the mold. The mold protrusions preferably provide an inverted image which is complementary to the intended macro-texture design or configuration. Injection molding is a well known technology and need not be described further here. The macro-indentation(s) is(are) useful in providing large flow channels for the polishing fluid, during the polishing operation.
An agent comprising a wax, hydrocarbon or other solid, semi-solid or liquid organic material can be applied to the mold to enhance release of the molded part after molding. A preferred mold release agent comprises a solid organic material and a solvent or liquid carrier. A particularly preferred mold release agent is a fluorocarbon dispersion, available from E. I. du Pont de Nemours and Company, Wilmington, Del., U.S.A. Preferred solvents or liquid carrier materials have a vapor pressure in the range of 0.1 to 14.7 pounds per square inch (xe2x80x9cpsixe2x80x9d), more preferably 1-12 psi and yet more preferably in the range of 4.5 to 5.5 psi. In a preferred embodiment, a wax, hydrocarbon or other non-polar solid organic material is dissolved or suspended in an organic solvent, preferably a non-polar organic solvent, such as mineral spirits, and applied as a mold release agent prior to the injection operation. Alternatively, an internal mold release agent can be used, which is incorporated directly into the pad material and aids in de-molding the pad after pad manufacture.
Pad surface topography is relatively consistent for pads of the present invention, because the mold surface remains generally the same for each pad produced by it. Pads produced by many conventional methods are generally more prone to variations and inconsistencies. Predictability of performance is an important aspect of a precision polishing pad. Pad consistency allows for more exacting standard operating procedures and therefore more productive (and reproducible) polishing operations.
After forming the pad""s polishing layer, including at least a part of the macro-texture, the outer surface can be further modified by adding a micro-texture. The micro-texture is preferably created by moving the polishing layer surface against the surface of an abrasive material. In one embodiment, the abrasive material is a rotating structure (the abrasive material can be round, square, rectangular, oblong or of any geometric configuration) having a plurality of rigid particles embedded (and preferably, permanently affixed) upon the surface. The movement of the rigid particles against the pad surface causes the pad surface to undergo plastic flow, fragmentation or a combination thereof (at the point of contact with the particles). The abrasive surface need not rotate against the pad surface; the abrasive surface can move against the pad in any one of a number of ways, including vibration, linear movement, random orbitals, rolling or the like.
The resulting plastic flow, fragmentation or combination thereof (due to the abrasive surface), creates a micro-texture upon the pad""s outer surface. The micro-texture can comprise a micro-indentation with a micro-protrusion adjacent to at least one side. In one embodiment, the micro-protrusions provide at least 0.1 percent of the surface area of the pad""s polishing surface, and the micro-indentations have an average depth of less than 50 microns, more preferably less than 10 microns, and the micro-protrusions have an average height of less than 50 microns and more preferably less than 10 microns. Preferably, such surface modification with an abrasive surface will cause minimal abrasion removal of the polishing layer, but rather merely plows furrows into the pad without causing a substantial amount, if any, of pad material to separate from the polishing layer. However, although less preferred, abrasion removal of pad material is acceptable, so long as a micro-texture is produced.
In an alternative embodiment, at least a portion of the micro-indentations or micro-protrusions may also be created during the molding process by incorporation of appropriate features into the mold. Formation of micro-texture and macro-texture during the fabrication of the pad can diminish or even negate the necessity of preconditioning break-in. Such formation also provides more controlled and faithful replication of the micro-texture as compared to surface modification subsequent to pad creation.
The pads of the present invention are preferably used in combination with a polishing fluid, such as a polishing slurry, for such processes as chemical mechanical polishing of a metal, silicon or silicon dioxide substrate. During polishing, the polishing fluid is placed between the pad""s polishing surface and the substrate to be polished. As the pad is moved relative to the substrate being polished, the micro-indentations allow for improved polishing fluid flow along the interface (between the pad and the substrate to be polished). The improved flow of polishing fluid generally allows for more efficient and effective polishing performance. Also, during polishing, the substrate and the polishing layer are pressed against each other, most usually using a pressure between the substrate and the polishing layer of greater than 0.1 kilograms per square meter.
Since at least some of the macro-texture is not created by an external means (such as by machining), the macro-texture is less prone to macro-defects, such as burrs or protrusions. This has been found to improve polishing pad performance by providing a polishing surface having very low levels of macro-defects and by substantially diminishing debris trapped in the macro-indentations that would otherwise inhibit the flow of polishing fluid.
In use, the pads of the present invention are preferably attached to a platen and then brought sufficiently proximate with a workpiece to be polished or planarized. Surface irregularities are removed at a rate which is dependent upon a number of parameters, including: pad pressure on the workpiece surface (or vice versa); the speed at which the pad and workpiece move in relation to one another; and the components of the polishing fluid.
As the pad polishes, the micro-texture can experience abrasion removal or plastic flow (the micro-protrusions are flattened or are otherwise less pronounced), which can diminish polishing performance. The micro-protrusions are then preferably re-formed with further conditioning, such as by moving the pad against an abrasive surface again and causing the material to once again form furrows. Such reconditioning is generally not as rigorous and/or not required as often for pads of the present invention, relative to may common prior art pads.
The preferred abrasive surface for conditioning is a disk which is preferably metal and which is preferably embedded with diamonds of a size in the range of 1 micron to 0.5 millimeters. During conditioning, the pressure between the conditioning disk and the polishing pad is preferably between 0.1 to about 25 pounds per square inch. The disk""s speed of rotation is preferably in the range of 1 to 1000 revolutions per minute.
A preferred conditioning disk is a four inch diameter, 100 grit diamond disk, such as the RESI(copyright) Disk manufactured by R. E. Science, Inc. Optimum conditioning was attained when the downforce was 10 lbs per square inch, platen speed was 75 rpm, the sweep profile was bell-shaped, the number of preconditioning break-in sweeps was 15 and the number of replenishing conditioning sweeps between wafers was 15.
Optionally, conditioning can be conducted in the presence of a conditioning fluid, preferably a water based fluid containing abrasive particles.
The polishing fluid is preferably water based and may or may not require the presence of abrasive particles, depending upon the composition of the polishing layer. For example, a polishing layer comprising abrasive particles may not require abrasive particles in the polishing fluid.

Polishing pads and methods relating thereto